The research proposed for this K23 is to evaluate the immediate cardiovascular effects of two challenges in overweight and lean children. The first challenge will be a single high fat meal and the second challenge will be a single bout of exercise followed by a high fat meal. This proposal is novel since instead of looking at children in their resting and fasted states, it involves examining children in their "active" metabolic and physiologic states. The overall aim of this work is to increase the understanding of mechanisms leading to cardiovascular dysfunction in overweight children and whether pre-prandial exercise may ameliorate the effects of their high fat environments. The overall hypothesis is that a single high fat meal in children will lead to vascular dysfunction which will be more pronounced in overweight children. In addition, a single bout of preprandial exercise will immediately improve vascular function both before and after a high fat meal. The public health effects of obesity are devastating, threatening to reverse the decades-long progress that researchers and clinicians have made in reducing death from cardiovascular disease. Traditionally cardiac derangements from obesity have been thought to develop in adulthood after decades of long standing obesity. However, at least one cardiac risk factor is already present in over half of overweight children. In addition, even more startling results are starting to show changes in cardiac geometry and vascular function. There is no doubt that diet and exercise play a role in the pediatric obesity epidemic, but the immediate impact of a high fat diet and lack of preceding exercise on cardiovascular function is poorly understood. Those gaps in knowledge will begin to be addressed by this research. The candidate's drive and initiative for research is demonstrated by having recently completed an NIH funded masters program in Epidemiology while concurrently completing her Pediatric Cardiology fellowship. In addition, she has further dedicated her time to research by being a participant on the NIH loan repayment program. Her master's thesis involved work on two populations of overweight and extremely overweight children and this current proposal will build on that previously gained knowledge. Her goals for this K23 are to increase her understanding and training in cardiovascular effects of pediatric obesity, non-invasive imaging modalities, and pathology associated with diet and exercise in order to understand, assess, and improve the cardiovascular health of obese children. The combined experience and skills acquired from her career .development plan and research will provide the early career support necessary for a successful independent clinical research career in the important areas of pediatric obesity and preventative medicine.